Alternating-current-motor control.



Y W. B. POTTER.

"ALTERNATING CURRENT MOTOR CONTROL.

" APPLICATION FILED APR. 2, 1910.

1,041,3 I I Patenteaocuzzwlz.

J l/yjz'zvzsaz'af INVENTUR PK'LLLAM .HPUTTEH.

if," l -1 UNITED STATES PATENT OFFICE.

' i wintinivr n. roman, or scHENncrhnY, NEW YORK, AssIGNon 'ro GENERAL ELEC'IItIC COMPANY, A CORPORATION on NEW YORK.

.ALIII'ERNA'JJING-CTJ'IitItlEhVIf-IVJIOTOR CONTROL.

Specification of Letters Patent.

I v i Patented Oct. 22, 1912. Application filed April 2,1910. Serial No. 552,941.

i To allwhomjtt may concern:

- Be it knownthat 1, WILLIAM B. Poms,-

a citizen of the United States, residing at" I Schenectady, county offschenectady, State 5 of a New York, have invented certain new :jl I fiftrol-System arranged in accordance with my jture, B-the exciting winding, r i s Yi GIl Bg .Wi' ing of an alterq-nating'current motor. J

'1) represents transformer winding servand useful Improvements inAlternating- I Current Motor Control, of which the fol lowing is a specification. I s ,c My invention relates to the control of alternating current motors of the compensated series type,;thatis,-to motors-havin an ar- 7 l.1nature pl-wicked with commutator rushes,

I an exciting. winding on the stator producing a-anagnetization at, right angles to the line It has been proposed heretofore to operfatefaflmotorof this, type as a repulsion motor, that is,fwith the armature brushes short-circuited, at starting, and for high .fspeedsnto open the short-circuit and impress shunt excitation on the compensating ..-,w1nd1n'g.

"My inventionconslsts 1n rendering this change ofconnections wholly automatic by s providingcircuit changing means Wholly independent of the manual control but responsive tospeed variation in the motor. 3 With such-an arrangement, the manual control consists "-simplyof switches vfor varying the voltageimpressed onthe motor to conf..- trol its speed, whil e the change in motor g *'onnections 'is made automatically at the" *W-i 'pi'oper' timeato give bestcommutation for jbothlow-andhighspeeds.

II [My invention, will bestbaunderstood by reference to the accompanying-drawing whichi'shows diagrammatically a' mm coning asax-source'ofcurrent, for the motor.

1E represents a'i manually operated con-- v ".troljling switch which is indicated diagram.

-a fmatically with it's contact-s developed on a nected .in shunt to the armature contactor F which connect represents thestrma and C the com plane surface. I This switch controls the windings.of-contactors F, F which serve to connect the motorto different po'ints on the transformer winding D and thereby to vary thev impressed voltage to control the motor speed.

The; motor connections are controlled by means of a relay device having a main windmg connected in shunt to the exciting winding B and an opposing wind' a con- The contacts of this relay device control a pair of relays G and H which h-ave icontacts arranged as shown. J represents a'resistanceflwhic' the transition fromfl'oneset nections to the other; V. At starting the switchE is moved into its first position, energizing rthe right hand s the mhtor to the transformer tapof lowest voltage. At starting the voltage drop in the armature A is comparatively low and thatin the exciting winding B is comparatively high. Themain winding 6 of the relay device is, consequently, stronglyenergized and pulls up the plunger, moving theicontact to the other position thanthat; shown; A' circuit is thereby closedfrom the-lower terminal of transformer I), through the upper contacts of thejrelay device, thewindingof relay G and the lower. contactsof rela H to the H transformer winding Relay is, there'- fore, energized pulls upi its contacts,

sho'rt-circuiting the motor .;armature brushes through its upper contact 9:1].The motor,

consequently; starts as a. repulsion motor with the brushes of the armatureshortcir'cuit ed. A's .switchlE'. ie ,m'ovedlto its' other positions the voltage. impressed onthe motor is gradually increased and the motor is accelerated. As the motor speed increases, the motor-"current decreases and the voltage drop in exciting winding B decreases. Com sequently, winding 6 of therelay deviceis weakened until at a predetermmed speed -it no longeris able to holdup the fillll g I i The contact of-the device falls',.-br.ea g the its contact. The hontdctsg? and g are yieldingly mounted as indioatedso that I contact 9' closes' before'jcontactfg opens.

-When contact 9 c1oses,'a circuit'is established from the junction of. compensating V winding .6 and motor armature A through contact 9 closing a circuit through relay H; This relay,

contact-and short-circuits resistance J. A

- be decreased and the current increased sufshunt excitation is thus impressed directly on winding C from the transformer.

Winding a serves merely to hold the.

plunger down after it has been released by winding Z andafter contact 9 has opened. Thus, this winding serves to prevent any tendency to chattering: in the relay device.

Of course if the speed of the motor should enable Winding Z) to overpower ficiently to the relay would operate to shortwinding a,

" circuit the motor armature brushes precisely as at starting when the speed is zero.

By my invention as above described the chahge 1n connections of the motor is made 1 wholly automatic and entirely independent of the manual control.

Although for the sake of simplicity I have shown only one motor in the drawing, it is obvlous that any number of motors may be simultaneously controlled in the manner described for the" one motor.

I do not desire to limit myself to the parti'cular connections and arrangement of parts shown and described, but aim, in the appended claims, to cover all modifications which are within the scope ofmy invention.

What' I claim as new and desire to secure Letters Patent of the United States, is

1. In combination with an alternating current motor of the commutator type and a source of current therefor, manually controlled means for connecting said motor to said source and for varying the motor speed, and automatic means, independent of the manual control and responsive to variation in the electrical-condition of a winding of the motor, for short-circuiting the motor armature brushes. atlow speeds and opening the short-circuit at hi'gh speeds.

2. In combination with an alternating current motor of the commutator type provided with brushes and a 'source of current therefor, manually controlled means for connecting the motor to'the source and varying the motor speed, a relay havinga windthe short-circuit" ing connected in parallel with a winding of the motor, the voltage of which varies with .the motor speed, and connect-ions controlled solely by said relay, independently of the manual control, for short-circuiting the motor arm 'ature brushes.

3. In combination with an alternating current motor of thecompensated series type and a source of current therefor, manually controlled means for com'iecting the motor to the source and varying the motor speed, and automatic means, independent ofthe manual control and responsive to variatron 1n the motor speed, for short-circuiting the motor armature brushes at low speeds and opening the short-circuit and impress ing a shunt voltage on the compensating winding at high speeds.

4:. In combination with an alternating current motor of the compensated series type and asource of current theretor,m.anu-

ally controlled means for connectingthe m0- tor to the source and varying the motor speed, a relay having a winding connected in parallel with a winding of the motor, the voltage of which varies with the .motor speed, and connections v control, for short-circuiting the motor armature brushes when the relay contacts are 111,

one position andopening the short-circuit and impressing a. shunt voltage on the corn-v controlled solelyby. said relay, independently of the manuall pensating winding when the relay contacts I are in their other position.

5 In combination with an alternating current motor of the compensated series type. and a source of current therefor, manually controlled means vfor connecting the motor to the source and varying the motor speed, a relay having a main winding connected inparallel with the exciting winding of the motor and an opposing winding connested in parallel with the motor armature, and connections controlled solely by said relay, independently of the manual control, for short-circuiting the motor armature brushes.

In witness whereof, I have hereunto set my hand this 1st day of April, 1910.

- WILLIAM B. POTTER. Witnesses:

BENJAMIN B. HULL, HELEN Onrono.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' ,Washlngton, D. 0.' 

